cddc
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LOL...your addiction is now cureless 
Darkvoice 336i & 336SE Tuberolling PartII
- Thread starter HeatFan12
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bcowen
Headphoneus Supremus
Never heard a J-tube in the 6AS7G family, but it looks like an RCA 6AS7G to me.
Not sure if it's a rebranded RCA, or manufactured according to RCA's design.
If it sounds like an RCA, I will stay away
I might have an RCA 6AS7G, but I'll have to look. Have a couple RCA 6AS7GA's (straight bottle) for sure. I'll take a look and see how they compare.
NEC was given a lot of help (and funding) in its early days by Western Electric. Hoping if this was licensed or rebranded that WE was behind it rather than RCA...
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JKDJedi
Headphoneus Supremus
Where do you find all these magnificent toys!? I did a quick look up (Google my go to search engine) and found a listing with this infoEver try one of these? Not sure who all might have made this particular type. Other than the Matsu 7DJ8 (not an uber-tube but pretty good for the money) I've not heard a Japanese-made tube that got me excited. But you never know where a diamond in the rough may lurk...
"Nippon Electric was a post WWII subsidary of Western Electric in Tokyo, Japan. The 6520 was a premium, high-reliability version of the 6AS7G. The only other company to manufacture this model of tube was Tung-Sol Chatham".
cddc
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My understanding of American 6520 tubes from what I read is that they were all made by TungSol/Chatham (possibly for computers). They come in 2 flavors, the ones with domino plates are basically 5998's, the others with 6AS7G plates are basically TS/Chatham 6AS7G's.
Now, this Japanese 6520 tube seems pretty interesting. It has a TungSol 6520 designation but with an RCA look, and a WE relationship.
The relationship between NEC and WE makes it even more interesting. If NEC used WE's design/tech, the tube would look like a TungSol manufactured WE 421A. But it has no domino plates. It looks like an RCA 6AS7G to me, albeit the shape of its glass bottle looks a little bit different.
Very interesting tube indeed
Now, this Japanese 6520 tube seems pretty interesting. It has a TungSol 6520 designation but with an RCA look, and a WE relationship.
The relationship between NEC and WE makes it even more interesting. If NEC used WE's design/tech, the tube would look like a TungSol manufactured WE 421A. But it has no domino plates. It looks like an RCA 6AS7G to me, albeit the shape of its glass bottle looks a little bit different.
Very interesting tube indeed
bcowen
Headphoneus Supremus
I just stumbled across these on Ebay. I have 5998's and 421A's in my watch list and these popped up down at the bottom in the 'similar items' area. Did some (very) quick poking around and noted the relationship with WE which got me interested. Seller was asking way more than I wanted to pay for a treasure hunt, so I shot him an offer at half of his asking price. Honestly expected him to get pissed off and not even respond at all
, but surprisingly he accepted about 30 minutes later. So here they are, and luckily they both test out very nicely.Don't have any RCA 6AS7G's so direct comparisons with an ST bottle aren't possible. The RCA 6AS7GA is entirely different, but that may be a result of the bottle shape. Note the TS 6080 and RCA 6080 I have are identical in every detail. So one made the tube for the other...
cddc
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Very interesting story on your purchase...
eBay is a mine field...sometimes people can find real good deals, but sometimes liars and duds.
Rebranding is very common in tubes, 6080 is no exception. You are right TungSol and the RCA on the right are identical, they are both RCA 6080's I believe. I also think the RCA with orange print is actually Sylvania 6080.
So I think from left to right you have: NEC 6AS7G ----------- RCA 6080 (rebranded as TungSol) -----------Sylvania 6080 (rebranded as RCA) -------------RCA 6080
eBay is a mine field...sometimes people can find real good deals, but sometimes liars and duds.
Rebranding is very common in tubes, 6080 is no exception. You are right TungSol and the RCA on the right are identical, they are both RCA 6080's I believe. I also think the RCA with orange print is actually Sylvania 6080.
So I think from left to right you have: NEC 6AS7G ----------- RCA 6080 (rebranded as TungSol) -----------Sylvania 6080 (rebranded as RCA) -------------RCA 6080
bcowen
Headphoneus Supremus
Very interesting story on your purchase...
eBay is a mine field...sometimes people can find real good deals, but sometimes liars and duds.
Rebranding is very common in tubes, 6080 is no exception. You are right TungSol and the RCA on the right are identical, they are both RCA 6080's I believe. I also think the RCA with orange print is actually Sylvania 6080.
So I think from left to right you have: NEC 6AS7G ----------- RCA 6080 (rebranded as TungSol) -----------Sylvania 6080 (rebranded as RCA) -------------RCA 6080
You're spot on with the Ebay mine field thing. I've been buying tubes on Ebay for probably 20+ years...but I've also had a good tube tester for 20+ years (and learned how to calibrate it myself). Personally, I wouldn't buy tubes on Ebay without a tester -- I'd pay more and go to a trusted dealer. But that's just me. There are some very good sellers on Ebay, but they are hopelessly outnumbered by the charlatans and people that just found some tubes at a garage or estate sale. The latter can be a nice way to get some great tubes for cheap, but 1) only buy from the 'unknowing' if they accept returns so that 2) you can return the tubes if they test badly (with the tester you have).
I've found the best way to get good tubes cheap on Ebay is to make a watch list item for any tube types you're interested in. That way you get an email when new listings are put up and can pounce on something quickly (if warranted). If there's a deal to be had and I get to it first, it's gone. LOL!!
JKDJedi
Headphoneus Supremus
My windows 10 update knocked out the Topping D10 drivers.. (sob) and it seems like the Topping website is down for now... So getting use to the back up unit.. sort changes the sound signature of everything in a suttle way, gonna be a tube rolling weekend ahead
sort changes the sound signature of everything in a suttle way, gonna be a tube rolling weekend ahead 
bcowen
Headphoneus Supremus
My windows 10 update knocked out the Topping D10 drivers.. (sob) and it seems like the Topping website is down for now... So getting use to the back up unit..
Bummer on the update thing, but nice that you have a backup!
Received the Tung Sol 7236 tube today. Tests great...very much appears to be NOS. But construction is very different from the Cetron. About the only thing in common is the medium gray box plates, but even with those the Tung Sols plates are longer with different extensions. The TS has a taller bottle, dual rectangular getter holders up top (Cetron has dual rings), different micas, etc etc. Possible the year of manufacture has something to do with it but I doubt it. Guessing the Cetrons were NOT made by Tung Sol. I'll be quite interested to see how they compare once I can listen to them.
JKDJedi
Headphoneus Supremus
How's the burn in going with the Cetron? How does it compare to the Tung Sol?
bcowen
Headphoneus Supremus
Don't know yet. Still waiting on the amp to listen to them in. Some of the non-electronic parts for this amp (like the transformer cover) are sourced from China, and for some weird reason there's been a delay on those.
Can't wait to hear these tubes, but as this will be my first OTL I don't have any other amps on hand to try them in.
Absoltuion
Head-Fier
Does anyone have photos of the transformer inside the SE? I was going to take of the cap off today but I don't have my soldering stations with me.
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JKDJedi
Headphoneus Supremus
You got the Darkvoice amp? -----------> https://drop.com/buy/dark-voice-366seDon't know yet. Still waiting on the amp to listen to them in. Some of the non-electronic parts for this amp (like the transformer cover) are sourced from China, and for some weird reason there's been a delay on those.
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